A woman's menstrual cycle can normally range anywhere between 23 and 35 days, states womentowomen.com. Every woman's menstrual cycle can be different, and irregular menstrual cycles are determined by what is regular for each individual. Irregular menstrual cycles can encompass missed periods, periods that occur too frequently, spotting or heavy bleeding. Many conditions can disrupt a regular menstrual cycle; these conditions all affect the hormone balance, which plays a role in menstruation.
Perimenopause
According to Marcelle Pick, an ob/gyn nurse practitioner, irregular menstrual cycles can be due to a hormone imbalance that is not related to menopause. Menopause is definitively diagnosed after a year of no menstrual periods, but prior to entering menopause, there is a period known as perimenopause. During perimenopause, irregular menstrual cycles may occur due to progesterone imbalances, says Pick. Progesterone is a hormone that controls the length and amount of bleeding during the menstrual cycle; when this hormone is out of balance, the menstrual cycle becomes irregular or abnormal.
Stress
An increase in the amount of stress can contribute to menstrual cycle irregularities because of cortisol fluctuations. During periods of stress, cortisol is secreted by the adrenal glands. Cortisol is a hormone that affects estrogen, progesterone and DHEA, according to Pick. Stress may not be solely emotional; eating disorders, drug use, over-exercising and dieting are also stressors on the body that affect cortisol levels.
Medical Conditions
Menstrual cycles can also be affected by medical conditions like epilepsy, thyroid problems and polycystic ovarian syndrome, or PCOS, according to the New York Times Health Guide. In PCOS, high amounts of androgens like testosterone are made, which alters the menstrual cycle. Hyperprolactinemia, or high levels of the hormone prolactin, can contribute to irregularities in menstruation because this hormone inhibits ovulation. According to the National Institute of Child Health and Human Development, premature ovarian failure, or POF, is a condition in which the ovaries stop functioning in a woman under 40 years of age. Women with POF may have no periods or very irregular periods.
Structural Problems
Abnormalities in the reproductive system can be a cause of irregular menstrual cycles, notes the New York Times Health Guide. Structural problems or scarring in the uterus can interrupt menstrual flow and in some cases, prevent menstruation. Uterine fibroids are non-cancerous tumors and can affect menstruation, causing very heavy periods, bleeding between periods and irregular cycles.
